Merge branch 'ps/odb-drop-whence' into next

The 'whence' field in 'struct object_info' has been removed,
refactoring backend-specific object information retrieval into an opt-
in 'struct object_info_source' structure.

* ps/odb-drop-whence:
  odb: document object info fields
  odb: drop `whence` field from object info
  treewide: convert users of `whence` to the new source field
  odb: add `source` field to struct object_info_source
  odb: make backend-specific fields optional
  packfile: thread odb_source_packed through packed_object_info()

builtin/cat-file.c

@@ -500,7 +500,7 @@ static void batch_object_write(const char *obj_name,
 			data->info.sizep = &data->size;
 
 		if (pack)
-			ret = packed_object_info(pack, offset, &data->info);
+			ret = packed_object_info(NULL, pack, offset, &data->info);
 		else
 			ret = odb_read_object_info_extended(the_repository->objects,
 							    &data->oid, &data->info,
@@ -837,8 +837,9 @@ static int batch_one_object_oi(const struct object_id *oid,
 			       void *_payload)
 {
 	struct for_each_object_payload *payload = _payload;
-	if (oi && oi->whence == OI_PACKED)
-		return payload->callback(oid, oi->u.packed.pack, oi->u.packed.offset,
+	if (oi && oi->source_infop->source->type == ODB_SOURCE_PACKED)
+		return payload->callback(oid, oi->source_infop->u.packed.pack,
+					 oi->source_infop->u.packed.offset,
 					 payload->payload);
 	return payload->callback(oid, NULL, 0, payload->payload);
 }
@@ -909,7 +910,10 @@ static void batch_each_object(struct batch_options *opt,
 						&payload, flags);
 		}
 	} else {
-		struct object_info oi = { 0 };
+		struct odb_source_info source_info;
+		struct object_info oi = {
+			.source_infop = &source_info,
+		};
 
 		for (source = the_repository->objects->sources; source; source = source->next) {
 			struct odb_source_files *files = odb_source_files_downcast(source);

builtin/index-pack.c

@@ -1825,11 +1825,16 @@ static void repack_local_links(void)
 
 	oidset_iter_init(&outgoing_links, &iter);
 	while ((oid = oidset_iter_next(&iter))) {
-		struct object_info info = OBJECT_INFO_INIT;
+		struct odb_source_info source_info;
+		struct object_info info = {
+			.source_infop = &source_info,
+		};
+
 		if (odb_read_object_info_extended(the_repository->objects, oid, &info, 0))
 			/* Missing; assume it is a promisor object */
 			continue;
-		if (info.whence == OI_PACKED && info.u.packed.pack->pack_promisor)
+		if (source_info.source->type == ODB_SOURCE_PACKED &&
+		    source_info.u.packed.pack->pack_promisor)
 			continue;
 
 		if (!cmd.args.nr) {

builtin/pack-objects.c

@@ -2463,7 +2463,7 @@ static void drop_reused_delta(struct object_entry *entry)
 
 	oi.sizep = &size;
 	oi.typep = &type;
-	if (packed_object_info(IN_PACK(entry), entry->in_pack_offset, &oi) < 0) {
+	if (packed_object_info(NULL, IN_PACK(entry), entry->in_pack_offset, &oi) < 0) {
 		/*
 		 * We failed to get the info from this pack for some reason;
 		 * fall back to odb_read_object_info, which may find another copy.
@@ -3820,7 +3820,7 @@ static int add_object_entry_from_pack(const struct object_id *oid,
 	ofs = nth_packed_object_offset(p, pos);
 
 	oi.typep = &type;
-	if (packed_object_info(p, ofs, &oi) < 0) {
+	if (packed_object_info(NULL, p, ofs, &oi) < 0) {
 		die(_("could not get type of object %s in pack %s"),
 		    oid_to_hex(oid), p->pack_name);
 	} else if (type == OBJ_COMMIT) {
@@ -4495,8 +4495,9 @@ static int add_object_in_unpacked_pack(const struct object_id *oid,
 				       void *data UNUSED)
 {
 	if (cruft) {
-		add_cruft_object_entry(oid, OBJ_NONE, oi->u.packed.pack,
-				       oi->u.packed.offset, NULL, *oi->mtimep);
+		add_cruft_object_entry(oid, OBJ_NONE, oi->source_infop->u.packed.pack,
+				       oi->source_infop->u.packed.offset, NULL,
+				       *oi->mtimep);
 	} else {
 		add_object_entry(oid, OBJ_NONE, "", 0);
 	}
@@ -4513,8 +4514,10 @@ static void add_objects_in_unpacked_packs(void)
 			 ODB_FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS |
 			 ODB_FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS,
 	};
+	struct odb_source_info source_info;
 	struct object_info oi = {
 		.mtimep = &mtime,
+		.source_infop = &source_info,
 	};
 
 	odb_prepare_alternates(to_pack.repo->objects);
@@ -5036,10 +5039,14 @@ static int option_parse_cruft_expiration(const struct option *opt UNUSED,
 
 static int is_not_in_promisor_pack_obj(struct object *obj, void *data UNUSED)
 {
-	struct object_info info = OBJECT_INFO_INIT;
+	struct odb_source_info source_info;
+	struct object_info info = {
+		.source_infop = &source_info,
+	};
+
 	if (odb_read_object_info_extended(the_repository->objects, &obj->oid, &info, 0))
 		BUG("should_include_obj should only be called on existing objects");
-	return info.whence != OI_PACKED || !info.u.packed.pack->pack_promisor;
+	return source_info.source->type != ODB_SOURCE_PACKED || !source_info.u.packed.pack->pack_promisor;
 }
 
 static int is_not_in_promisor_pack(struct commit *commit, void *data) {

commit-graph.c

@@ -1538,7 +1538,7 @@ static int add_packed_commits(const struct object_id *oid,
 	struct object_info oi = OBJECT_INFO_INIT;
 
 	oi.typep = &type;
-	if (packed_object_info(pack, offset, &oi) < 0)
+	if (packed_object_info(NULL, pack, offset, &oi) < 0)
 		die(_("unable to get type of object %s"), oid_to_hex(oid));
 
 	return add_packed_commits_oi(oid, &oi, data);

odb.c

@@ -691,8 +691,8 @@ static int oid_object_info_convert(struct repository *r,
 			return -1;
 		}
 	}
-	input_oi->whence = new_oi.whence;
-	input_oi->u = new_oi.u;
+	if (input_oi->source_infop)
+		*input_oi->source_infop = *new_oi.source_infop;
 	return ret;
 }
 

odb.h

@@ -260,33 +260,19 @@ int odb_pretend_object(struct object_database *odb,
 		       void *buf, size_t len, enum object_type type,
 		       struct object_id *oid);
 
-struct object_info {
-	/* Request */
-	enum object_type *typep;
-	size_t *sizep;
-	off_t *disk_sizep;
-	struct object_id *delta_base_oid;
-	void **contentp;
+/*
+ * Object database source information that can be used to uniquely identify an
+ * object and learn more about how exactly it is stored.
+ */
+struct odb_source_info {
+	/* The source that this object has been looked up from. */
+	struct odb_source *source;
 
 	/*
-	 * The time the given looked-up object has been last modified.
-	 *
-	 * Note: the mtime may be ambiguous in case the object exists multiple
-	 * times in the object database. It is thus _not_ recommended to use
-	 * this field outside of contexts where you would read every instance
-	 * of the object, like for example with `odb_for_each_object()`. As it
-	 * is impossible to say at the ODB level what the intent of the caller
-	 * is (e.g. whether to find the oldest or newest object), it is the
-	 * responsibility of the caller to disambiguate the mtimes.
+	 * Backend-specific information about the specific object. This can be
+	 * used for example to uniquely identify a given object in case it
+	 * exists multiple times.
 	 */
-	time_t *mtimep;
-
-	/* Response */
-	enum {
-		OI_CACHED,
-		OI_LOOSE,
-		OI_PACKED,
-	} whence;
 	union {
 		/*
 		 * struct {
@@ -309,6 +295,52 @@ struct object_info {
 	} u;
 };
 
+/*
+ * The object info contains the query and response that is to be used for
+ * functions that end up reading object information. Callers are expected to
+ * populate pointers whose information they want to request.
+ */
+struct object_info {
+	/* The object type. */
+	enum object_type *typep;
+
+	/* The inflated object size in bytes. */
+	size_t *sizep;
+
+	/* The object size as stored on disk. */
+	off_t *disk_sizep;
+
+	/*
+	 * The base the object is deltified against, in case it is stored as a
+	 * delta.
+	 */
+	struct object_id *delta_base_oid;
+
+	/* The object contents. Ownership of memory goes over to the caller. */
+	void **contentp;
+
+	/*
+	 * The time the given looked-up object has been last modified.
+	 *
+	 * Note: the mtime may be ambiguous in case the object exists multiple
+	 * times in the object database. It is thus _not_ recommended to use
+	 * this field outside of contexts where you would read every instance
+	 * of the object, like for example with `odb_for_each_object()`. As it
+	 * is impossible to say at the ODB level what the intent of the caller
+	 * is (e.g. whether to find the oldest or newest object), it is the
+	 * responsibility of the caller to disambiguate the mtimes.
+	 */
+	time_t *mtimep;
+
+	/*
+	 * Backend-specific information that tells the caller where exactly an
+	 * object was looked up from. This information should help disambiguate
+	 * object lookups in case the same object exists in multiple sources,
+	 * or multiple times in the same source.
+	 */
+	struct odb_source_info *source_infop;
+};
+
 /*
  * Initializer for a "struct object_info" that wants no items. You may
  * also memset() the memory to all-zeroes.

odb/source-inmemory.c

@@ -52,7 +52,8 @@ static void populate_object_info(struct odb_source_inmemory *source,
 		*oi->contentp = xmemdupz(object->buf, object->size);
 	if (oi->mtimep)
 		*oi->mtimep = 0;
-	oi->whence = OI_CACHED;
+	if (oi->source_infop)
+		oi->source_infop->source = &source->base;
 }
 
 static int odb_source_inmemory_read_object_info(struct odb_source *source,

odb/source-loose.c

@@ -196,8 +196,8 @@ out:
 			oi->typep = NULL;
 		if (oi->delta_base_oid)
 			oidclr(oi->delta_base_oid, loose->base.odb->repo->hash_algo);
-		if (!ret)
-			oi->whence = OI_LOOSE;
+		if (oi->source_infop && !ret)
+			oi->source_infop->source = &loose->base;
 	}
 
 	return ret;

odb/source-packed.c

@@ -59,7 +59,7 @@ static int odb_source_packed_read_object_info(struct odb_source *source,
 	if (!oi)
 		return 0;
 
-	ret = packed_object_info(e.p, e.offset, oi);
+	ret = packed_object_info(packed, e.p, e.offset, oi);
 	if (ret < 0) {
 		mark_bad_packed_object(e.p, oid);
 		return -1;
@@ -99,7 +99,7 @@ static int odb_source_packed_for_each_object_wrapper(const struct object_id *oid
 		off_t offset = nth_packed_object_offset(pack, index_pos);
 		struct object_info oi = *data->request;
 
-		if (packed_object_info_with_index_pos(pack, offset,
+		if (packed_object_info_with_index_pos(data->store, pack, offset,
 						      &index_pos, &oi) < 0) {
 			mark_bad_packed_object(pack, oid);
 			return -1;

pack-bitmap.c

@@ -1877,7 +1877,7 @@ static unsigned long get_size_by_pos(struct bitmap_index *bitmap_git,
 			ofs = pack_pos_to_offset(pack, pos);
 		}
 
-		if (packed_object_info(pack, ofs, &oi) < 0) {
+		if (packed_object_info(NULL, pack, ofs, &oi) < 0) {
 			struct object_id oid;
 			nth_bitmap_object_oid(bitmap_git, &oid,
 					      pack_pos_to_index(pack, pos));

packfile.c

@@ -1324,7 +1324,8 @@ static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
 	hashmap_add(&delta_base_cache, &ent->ent);
 }
 
-int packed_object_info_with_index_pos(struct packed_git *p, off_t obj_offset,
+int packed_object_info_with_index_pos(struct odb_source_packed *source,
+				      struct packed_git *p, off_t obj_offset,
 				      uint32_t *maybe_index_pos, struct object_info *oi)
 {
 	struct pack_window *w_curs = NULL;
@@ -1420,23 +1421,28 @@ int packed_object_info_with_index_pos(struct packed_git *p, off_t obj_offset,
 			oidclr(oi->delta_base_oid, p->repo->hash_algo);
 	}
 
-	oi->whence = OI_PACKED;
-	oi->u.packed.offset = obj_offset;
-	oi->u.packed.pack = p;
+	if (oi->source_infop) {
+		if (!source)
+			BUG("cannot request source without an owning source");
+		oi->source_infop->source = &source->base;
 
-	switch (type) {
-	case OBJ_NONE:
-		oi->u.packed.type = PACKED_OBJECT_TYPE_UNKNOWN;
-		break;
-	case OBJ_REF_DELTA:
-		oi->u.packed.type = PACKED_OBJECT_TYPE_REF_DELTA;
-		break;
-	case OBJ_OFS_DELTA:
-		oi->u.packed.type = PACKED_OBJECT_TYPE_OFS_DELTA;
-		break;
-	default:
-		oi->u.packed.type = PACKED_OBJECT_TYPE_FULL;
-		break;
+		oi->source_infop->u.packed.offset = obj_offset;
+		oi->source_infop->u.packed.pack = p;
+
+		switch (type) {
+		case OBJ_NONE:
+			oi->source_infop->u.packed.type = PACKED_OBJECT_TYPE_UNKNOWN;
+			break;
+		case OBJ_REF_DELTA:
+			oi->source_infop->u.packed.type = PACKED_OBJECT_TYPE_REF_DELTA;
+			break;
+		case OBJ_OFS_DELTA:
+			oi->source_infop->u.packed.type = PACKED_OBJECT_TYPE_OFS_DELTA;
+			break;
+		default:
+			oi->source_infop->u.packed.type = PACKED_OBJECT_TYPE_FULL;
+			break;
+		}
 	}
 
 	ret = 0;
@@ -1446,10 +1452,11 @@ out:
 	return ret;
 }
 
-int packed_object_info(struct packed_git *p, off_t obj_offset,
+int packed_object_info(struct odb_source_packed *source,
+		       struct packed_git *p, off_t obj_offset,
 		       struct object_info *oi)
 {
-	return packed_object_info_with_index_pos(p, obj_offset, NULL, oi);
+	return packed_object_info_with_index_pos(source, p, obj_offset, NULL, oi);
 }
 
 static void *unpack_compressed_entry(struct packed_git *p,

packfile.h

@@ -320,9 +320,11 @@ extern int do_check_packed_object_crc;
  * Look up the object info for a specific offset in the packfile.
  * Returns zero on success, a negative error code otherwise.
  */
-int packed_object_info(struct packed_git *pack,
+int packed_object_info(struct odb_source_packed *source,
+		       struct packed_git *pack,
 		       off_t offset, struct object_info *);
-int packed_object_info_with_index_pos(struct packed_git *p, off_t obj_offset,
+int packed_object_info_with_index_pos(struct odb_source_packed *source,
+				      struct packed_git *p, off_t obj_offset,
 				      uint32_t *maybe_index_pos, struct object_info *oi);
 
 void mark_bad_packed_object(struct packed_git *, const struct object_id *);

reachable.c

@@ -234,8 +234,9 @@ static int add_recent_object(const struct object_id *oid,
 
 	add_pending_object(data->revs, obj, "");
 	if (data->cb) {
-		if (oi->whence == OI_PACKED)
-			data->cb(obj, oi->u.packed.pack, oi->u.packed.offset, *oi->mtimep);
+		if (oi->source_infop->source->type == ODB_SOURCE_PACKED)
+			data->cb(obj, oi->source_infop->u.packed.pack,
+				 oi->source_infop->u.packed.offset, *oi->mtimep);
 		else
 			data->cb(obj, NULL, 0, *oi->mtimep);
 	}
@@ -252,9 +253,11 @@ int add_unseen_recent_objects_to_traversal(struct rev_info *revs,
 	unsigned flags;
 	enum object_type type;
 	time_t mtime;
+	struct odb_source_info source_info;
 	struct object_info oi = {
 		.mtimep = &mtime,
 		.typep = &type,
+		.source_infop = &source_info,
 	};
 	int r;
 

t/helper/test-bitmap.c

@@ -52,7 +52,7 @@ static int add_packed_object(const struct object_id *oid,
 
 	entry = packlist_alloc(packed, oid);
 	entry->idx.offset = nth_packed_object_offset(pack, pos);
-	if (packed_object_info(pack, entry->idx.offset, &oi) < 0)
+	if (packed_object_info(NULL, pack, entry->idx.offset, &oi) < 0)
 		die("could not get type of object %s",
 		    oid_to_hex(oid));
 	oe_set_type(entry, type);